RFR: JDK-8152690: main thread does not have native thread name

[Yasumasa Suenaga]

Hi,

I uploaded new webrev.
Could you review it?

   http://cr.openjdk.java.net/~ysuenaga/JDK-8152690/webrev.01/


Thanks,

Yasumasa


On 2016/03/30 19:10, Robbin Ehn wrote:
> Hi,
>
> On 03/30/2016 11:41 AM, Yasumasa Suenaga wrote:
>> Hi Robbin,
>>
>> 2016/03/30 18:22 "Robbin Ehn" <robbin.ehn at oracle.com
>> <mailto:robbin.ehn at oracle.com>>:
>>  >
>>  > Hi Yasumasa,
>>  >
>>  >
>>  > On 03/25/2016 12:48 AM, Yasumasa Suenaga wrote:
>>  >>
>>  >> Hi Robbin,
>>  >> 2016/03/25 1:51 "Robbin Ehn" <robbin.ehn at oracle.com
>> <mailto:robbin.ehn at oracle.com>
>>  >> <mailto:robbin.ehn at oracle.com <mailto:robbin.ehn at oracle.com>>>:
>>  >>
>>  >>  >
>>  >>  > Hi Yasumasa,
>>  >>  >
>>  >>  > I'm not sure why you don't set it:
>>  >>  >
>>  >>  > diff -r ded6ef79c770 src/share/vm/runtime/thread.cpp
>>  >>  > --- a/src/share/vm/runtime/thread.cpp   Thu Mar 24 13:09:16 2016
>> +0000
>>  >>  > +++ b/src/share/vm/runtime/thread.cpp   Thu Mar 24 17:40:09 2016
>> +0100
>>  >>  > @@ -3584,6 +3584,7 @@
>>  >>  >    JavaThread* main_thread = new JavaThread();
>>  >>  >    main_thread->set_thread_state(_thread_in_vm);
>>  >>  >    main_thread->initialize_thread_current();
>>  >>  > +  main_thread->set_native_thread_name("main");
>>  >>  >    // must do this before set_active_handles
>>  >>  >    main_thread->record_stack_base_and_size();
>>  >>  >    main_thread->set_active_handles(JNIHandleBlock::allocate_block());
>>  >>  >
>>  >>  > here instead? Am I missing something?
>>  >>
>>  >> Native thread name is the same to thread name in Thread class.
>>  >> It is set in c'tor in Thread or setName().
>>  >> If you create new thread in Java app, native thread name will be set at
>>  >> startup. However, main thread is already starte in VM.
>>  >> Thread name for "main" is set in create_initial_thread().
>>  >> I think that the place of setting thrrad name should be the same.
>>  >
>>  >
>>  > Yes, I see your point. But then something like this is nicer, no?
>>  >
>>  > --- a/src/share/vm/runtime/thread.cpp   Tue Mar 29 09:43:05 2016 +0200
>>  > +++ b/src/share/vm/runtime/thread.cpp   Wed Mar 30 10:51:12 2016 +0200
>>  > @@ -981,6 +981,7 @@
>>  >  // Creates the initial Thread
>>  >  static oop create_initial_thread(Handle thread_group, JavaThread*
>> thread,
>>  >                                   TRAPS) {
>>  > +  static const char* initial_thread_name = "main";
>>  >    Klass* k =
>> SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true,
>> CHECK_NULL);
>>  >    instanceKlassHandle klass (THREAD, k);
>>  >    instanceHandle thread_oop =
>> klass->allocate_instance_handle(CHECK_NULL);
>>  > @@ -988,8 +989,10 @@
>>  >    java_lang_Thread::set_thread(thread_oop(), thread);
>>  >    java_lang_Thread::set_priority(thread_oop(), NormPriority);
>>  >    thread->set_threadObj(thread_oop());
>>  > -
>>  > -  Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
>>  > +
>>  > +  thread->set_native_thread_name(initial_thread_name);
>>  > +
>>  > +  Handle string =
>> java_lang_String::create_from_str(initial_thread_name, CHECK_NULL);
>>  >
>>  >    JavaValue result(T_VOID);
>>  >    JavaCalls::call_special(&result, thread_oop,
>>
>> Okay, I will upload new webrev later.
>
> Thanks!
>
>>
>>  >>  > The launcher seem to name itself 'java' and naming this thread just
>>  >>  > 'main' is confusing to me.
>>  >>  >
>>  >>  > E.g. so main thread of the process (and thus the process) is
>> 'java' but
>>  >>  > first JavaThread is 'main'.
>>  >>
>>  >> The native main thread in the process is not JavaThread. It is waiting
>>  >> for ending of Java main thread with pthread_join().
>>  >> set_native_thread_name() is for JavaThread. So I think that we do not
>>  >> need to call it for native main thread.
>>  >
>>  >
>>  > Not sure if we can change it anyhow, since we want java and native
>> name to be the same and java thread name might have some dependents.
>>  >
>>  > The name is visible in e.g. /proc.
>>  >
>>  > $ ps H -C java -o 'pid tid comm' | head -4
>>  >   PID   TID COMMAND
>>  >  6423  6423 java
>>  >  6423  6424 main
>>  >  6423  6425 GC Thread#0
>>  >
>>  > It would be nice with something like 'Java Main Thread'.
>>
>> I do not think so.
>> Native main thread might not be a Java launcher - e.g. Apache
>> commons-daemon, JNI application, etc.
>>
>> If you want to change native main thread name, I think that we have to
>> change Java launcher code.
>> Should I include it in new webrev?
>
> No
>
> Thanks again!
>
> /Robbin
>
>>
>> Thanks,
>>
>> Yasumasa
>>
>>  > Thanks
>>  >
>>  > /Robbin
>>  >
>>  >
>>  >>
>>  >> Thanks,
>>  >>
>>  >> Yasumasa
>>  >>
>>  >>  > Thanks!
>>  >>  >
>>  >>  > /Robbin
>>  >>  >
>>  >>  > On 03/24/2016 03:26 PM, Yasumasa Suenaga wrote:
>>  >>  > > Hi all,
>>  >>  > >
>>  >>  > > HotSpot for Linux will set thread name via pthread_setname_np().
>>  >>  > > However, main thread does not have it.
>>  >>  > >
>>  >>  > > All JavaThread have native name, and main thread is JavaThread.
>>  >>  > > For consistency, main thread should have native thread name.
>>  >>  > >
>>  >>  > > I uploaded a webrev. Could you review it?
>>  >>  > >
>>  >>  > > http://cr.openjdk.java.net/~ysuenaga/JDK-8152690/webrev.00/
>>  >>  > >
>>  >>  > > I cannot access JPRT.
>>  >>  > > So I need a sponsor.
>>  >>  > >
>>  >>  > >
>>  >>  > > Thanks,
>>  >>  > >
>>  >>  > > Yasumasa
>>  >>  > >
>>  >>
>>